Diffusion flame combustion using liquid fuel



Oct. 24, 1933. A L, KLEES 1,931,927

DIFFUSION FLAME COMBUSTION USING LIQUID FUEL /IL/aeRT L. 1.555

Patented Oct. 24, 1933 DIFFUSION FLAME coMBUsTIoN'sING LIQUID riUEL` Y YAlbertL. Klees, New York, N. Y., assigner to Combustion UtilitiesCorporation, New a corporation of Maine -f York, N. Y.,

Application Juiyfz, 1932. seriallNo. 620,576,

claims.' (clicca- 9) -ff Y.

This invention relates-to industrial high' temperature heating andheating-treating operations', and more specifically it concerns a novelmethod and apparatus ,for vutilizing normally liquid hyl drocarbons insuch commercial operationa-v It has especial utility in connection withthe heating of materials such as steel and Vother metals that aresubject to scaling due to the action thereon of highly heated productsof combustion.

l heating andheat-treating operations employing the diffusion-flame orluminous-llame type vof combustion, described in the copending patentapplication of S.. P. Burke, Serial No. 424,280, filed January 29,1930,-in accordance withl which process a fuel gas and air areseparately introduced into a furnace combustion chamber inindividualcontiguous streams or'strata, all moving in a common direction at suchcontrolled veloci- 20 ties as to avoid substantial turbulence duringcombustion.y The mixing of the gas and air occurs Within the furnacesubstantially entirely by interdiiusicn, so that at the various surfacesof contact of the Vgas andair; the conditions are 5 favorableforcombustion, but notelsewhere.

Industrial furnaces frequently mustrbe -operated at locations where auniform and yample flow of fuel gas of a uniform heat value is notavailable, or Where heavy loads on the fuel gas line. serving otherVinstallations interferes with the uniform, continuous supply of gas tothe burner of the diffusion. flame furnace.

Accordingly, among the moreimportant objects of the present inventionare: the adaptation of a normally liquid or liqueable hydrocarbon for aheating or heat-treating operation in accordance with the diffusionflame principle; tov provide for combusting fuel oil vapors wherebysteel'and other ,materials may be heated to high temperatures so Whileprotected from surface deterioration; and to provide for combusting anoil vapor-.gas'mixture of preselected B. t. u. content With air inproportions to give an overventilated flame, while preventing oil vaporcracking prior to introduction of the said vapors into the furnacaandwhile obtaining flame luminosity within the latter with its attendantadvantages and the production of a relatively long hot flame.Y c lAccording to a. preferred form of the present invention, a normallyliquid hydrocarbon or mixture thereof such as fuel oil,-or a readilylquefiable hydrocarbon such asbutane, eitheralone or dissolved in aheavier oil employed as a carrier liquid, is vaporized or atomized inthe presence i .of a highly-heated inert or `reducing gas, Vor'a Thepresent invention is intimately related-to gaseous mixture, and which isfree fromor very low in oxidizing constituents and preferably has a lowheating value. -Y Y The oii or liquid fuel may be preheated if desiredup to near but below the cracking temper- 6,0 ature of the hydrocarboncomponents of the fuel Vunder theiconditions of operation. The rate ofatomization of the fuel oil, and the volume and temperature of the'inertgas or flue gases admiXed therewith arev so adjusted that vaporizationof substantially all or a regulated part of the oil is `continuouslyeffected Within the gas stream, the

resultant fluid fuel then flowing to the fuel header of a diffusionllame burner mounted in a stream- Y line combustiton chamber of aheating or heat-'70 j sion flame burner of `a furnace of commercialdesign."V Such burner preferably -is designed to lintroduce into thefurnace sufiicient air for substantially complete combustionA of thevaporized fuel flowing "to it when the relative'velocities of the airand fuel' are approximately .thesamc Since undiluted oil vapor generallycontains .approximately 8000 B. t. u. per cu. fte-(and toburn Al cuit.'of this undiluted'vapor 8) cu. ft. ofrair 85 are require'da diusioniiame burner for use with this rich vapor v'is impractical. and requiresa ratio of total'air duct area tototal fuel vapor duct areav of 80:1,when providing approximately equaliiow velocities for the fuel vaporland'air. 90 Fuel ducts having a width or. thickness of only l/SG inchWould in some cases be necessitated. Such ducts could not functionproperly, vand would be impracticable from` a construction standpoint. Yv

In accordance with the present invention, fuel oil volatilization is soconducted that the resultant fluidvfuel mixture has a uniform controlledBl't. yu. value within the range from 200 to 2090Y t. u. per cufft.Mixtures having heating values.v Within the rangefrom 500 to 1900 B.t.u. per cu. ft. are particularly suitable for-use in present commercialheat-treatingoperations.

The mixed-oil vapors and gases fromA the oil vaporisation Zone,hereinafter described as the fluid fuelZ, then flow directly to theadjacent distributing head of a diusonl flamefurnace, during Whichiiow,any unvaporized liquid separates out and is removed.- 1 v Y 'f Withinthe diifusioni'iame burner the fluid 110 fuel passes for a brief periodin indirect heat exchange relation with either cold or preheated airflowingV through the burner ducts to the furnace. Preferably thetemperatures of the air and of the uid fuel are approximately the sameas they enter the respective air and fuel ducts,- although this is notessential.

The 'respective streams ofair and fluid fuel may flow to the combustionchamber either through parallel burner slots, or tubes or in parallel orconcentric tubular burner ducts,- and the velocities of the respectiveuid fuel and air streams are preferably approximately equal as theyenter the furnace. Considerable variation in the relative velocities ofthe fluid fuel and the air streams is possible, however, withoutcreating turbulence within the highly heated combustion zone.' Y

Within the furnace the streamline flow of the moving fluids is greatlyfacilitated by the high temperatures maintained therein, and by thedesign of the interior walls of the furnace, the same being soconstructed that the combustion chamber is substantially free ofmaterial abrupt changes in internal cross section.V

In the accompanying drawings:

Fig. l is a vertical section through one form of furnace exemplifyingthe invention;

Fig. 2 is a transverse vertical section through the furnace along thelines 2-2 of Fig. 1;

Fig. 3 is a longitudinal vertical. section through one form of diffusionflame burner assembly showing adjacent parts;

Fig. 4 is a fragmentary View in perspective of certain elements of theburner of Fig. 3;

Fig. 5 is a transverse vertical section through a modied form of burnerconstruction;

Fig. 6 is a plan View of the oil vaporizing and `atomizing apparatus ofFig. 1, somewhat modilied.

Referring now to the drawings, numeral 10 designates a furnace suitablylined with refrac tory material. An elongated heating and combustionchamber '12 of substantially uniform cross-section throughout its lengthhas a work receiving end wall 14, provided with an opening controlled bya door 16. f

The opposite end of the chamber 12 has a throat 18, the oor of which ispreferably disposed above the floor 20 of the chamber 12, a distanceapproximately equal to the height of the work to be heated therein. AWork charging device 22 is provided at the end 14 of the furnace forintroducing into the chamber 12 the material Vto be heated.Work-supporting tracks 24, which may be hollow and water-cooled, areprovided. An inclined work-discharging chute 26 having Vtherein a pairof spaced apart closing members 28, 3o is adapted to permit removal ofthe work While preventing substantial fluid flow between the furnace andthe outer atmosphere.

For removing the products of combustion from the chamber 12, a flue 32is provided in one or Vboth side walls of the furnace adjacent thework-receiving end thereof,-the same corn- ,municating through thepassageway 34 with a tion more particularly set out in Figs. 3 and 4,

there is provided a burner tube assembly comprising three connectedcasing sections 42, 44, and 46, forming respectively a cooling or heatber 52, separated by partitions 54 and 56, the conduits for` supplyingand removing cooling fluid and for supplying air being indicated at 58,59, and respectively. A plurality of tubular members 62 of heatresistant alloy and having sloping side walls and merging into eachother at their larger ends adjacent the burner outlet are mounted withinthe casing 42. Certain of the tubes are connected at their small endswith the chamber 52 through ducts 53 extending through the chamber 44.Others of the tubes open directly into the chamber 5@ and serve asair-conducting tubes. Y

Preferably all of the tubes in the lowermost row are connected with thechamber 52 in order that a flowing layer of protective vapors orreducing gases may be maintained upon and aroundthe material beingheated. Most of the tubes of course serve as air tubes, since a muchlarger volume of air than fuelvapors is needed for the substantiallycomplete combustion of the latter.

In the form shown in Figs, ,3 and 4, the arrangement preferably is suchthat each gas conducting duct above the two lowermost rows thereof iscompletely surrounded vby air conducting tubes, so that the various gasstrata or streams leaving the burner are completely surrounded by air. Y

According to the modification shownin Figs. 2 and 5, the burner assemblycomprises a housing 80, the same being divided intoa number ofsuperposed slots or ducts, S2, 84, by a plurality of thin partitions 86of heat resistant metal such as Rezistal. An air distributing header 83surrounds the housing 80 through a portion of its length and is suppliedthrough the conduit "60 with a current of air or its equivalent.Communication is maintained between the interior of the air header 88and each of the slots 82 through apertures 90 arranged at each side ofthe housing 80. The end of each duct 84 opposite the burner outlet isprovided with a plurality of apertures 92 establishing,communicationbetween these Yducts and the chamber 52.

In certain specific burner assemblies of the type Y shown in Figs. 2 and5, the lowerrnost fuel ducts have had effective heights of from 1/2 to 1inch; and the remaining fuel ducts have been in the range of from l/l to1 inch in height.

Housed within the furnace adjacent the inlet end of the burner assemblyis a vaporizing and atomizing chamber having therein a bladed rotor orfan 102 driven `by an 'electric motor or the like 104. The chamber 1Gois in open unrestricted communication with the fluid fuel distributingheader 52.. An oil spray nozzle 166 is adapted to distribute in finelydivided spray-form the fuel oil flowing thereto under pressure throughaline 103 and to impinge the same upon the blades of the fan 102;

The oil to be utilized in the process may be continuously drawn from theoil supply tank 110 through the valved line 108 tothe nozzle 106 by imeans of a pump 114 or its equivalent. 'if desired, cold oil may be fedunder pressure to the nozzle 106 through valvedconduit 11G; or oil befed to the nozzle'simultaneously from both the conduits 108 and 116. Abypass line -118 con- 'i trolled by a pressure-regulating valve bypasses the pump 114, to prevent accidental injury to the oil conduits orpump.V A portion of the oil conduit 108, in theform offa heating coil112, is

-:located inthe passageway 34 from whence the conduit leads throughtheflue gas passage 36, for the purpose of preheating theoilto thedesired temperature prior tov vaporizing it.

Aninsulated flue gas conduit 120 leads from the flue 32 to thevaporizing chamber 1GO, entering the latter either adjacent toorthroug-h the hub of the fan-102. A short valve-controlled fluegasconduit 1.22 connects the stack 38, at a point.

below the valve 40 therein, with the conduit 120 at apoint between avalve 124 inv that Aline and the chamber 100. I

For condensing and withdrawing from the fluid i fuel distributing header52 any unvaporized oil or any fluid condensate formed either whilebringing the furnace up to working temperature or thereafter,-there isprovided a liquid drain line 126 having therein a trap 128 of well knownconstruction and connecting with a transverse slot 127 in chamber 52. f

For introducing air into the section 'of the burner, ata controlledrate, there is provided a fan 1,30 having its outlet directly connectedwith the header 60.. `The inlet end of the fan is connected through avalved conduit 132 with the outer air, the said conduit extendingthrough the return flue 36 for the purpose of preheating the air toa'desired degree. The inlet end of the fan is also connected with avalved air conduit 134, for introducing cold air into the burner housingor for tempering the preheated air entering the fan through conduit 132.The fan preferably is operated by a'constant speed motor and regulaltion of the valves in air lines 132, 134,-although a variable speedmotor or itsequivalent may be used for vadjusting the rate of deliveryof air to the burner assembly.

For bringing the cold furnace up to the necessary operating temperatureand for producing flue gases which have suicient heat to effect the oilvaporization, in the apparatus described, there is provided a valvedfuel gas linel36 opening into the chamber 100. Fuel gas or oil or bothmay be introduced into the chamber 12 for the same purpose, through oneor more valved conduits 138 and combusted with air introduced therewiththrough conduit 140 or separately through conduit 60, for bringing thefurnace up to the desired operating temperature,-for example, 2200 to2400 F.

v As soon as the furnace has been brought to the desired temperature,and hot flue gases are being `hydrocarbons occursfor example to 700 F.,-

and the preheated oil is sprayed under pressurein finely dividedA formYupon jthe rapidly rotating vblades of the fanr102,while dispersed in astream of highly heated flue gases flowing from the fur- 'nace throughthe conduit 120. The rapidly spinning fan'blades break the oil into afog and the heat of the hot flue gases changes this Yfog into an oil gasor vapor. The resultant fluid fuel comprising a hot. mixture of oilvapors and` flue gases formedin the `vaporization zone of the furnacethen flows td the diffusion. flame burner therein, and thence to thecombustion or heattreating chamber. f Y

Byrthe suitable control of the temperature and the rate of introductionofr the flue gases into the vchamber 100, and of` the rate of iiowv andthe temperatureof the oil `passing the nozzle 106, a fluid combustiblemixture of uniform B.k t..u. value is caused toiiow continuousliTthrough the insulated tapered fuel distributing header 52 into andthroughthe burner ducts. Concurrently air under suitable low pressureenters the burner casing through the conduit and is distributed withinthe air tubes or ducts. These streams of fuel and air contact and areignited as they enter the furnace throat due to the high temperatureprevailing therein. Y Both fluid f uel and air streams are so regulatedthat they 110W at approximately the same velocity as they enter thefurnace throat. Mixing of the gas and air thereafter occurs principallyby vdiffusion as the combustion progressively proceeds at the surface ofcontact of the contiguous fuel and air streams. The totalcross-sectional area of the gas ducts and of the air ducts is soselectedl as to maintain the air and fuel streams at approximately equalvelocities and in suitable proportions for substantially completecombustion,-based on the composition of the hydrocarbon-containingvapors and of the oxygen-containing gas employed,-and the degree ofoverventilation, when such is desired.

Due to the high temperature of the furnace gases as theymove through theheating chamber, and due to a furnace construction free from Vabruptchanges in the transverse cross-section of the flowing gases,turbulencev is still further inhibited. This prevents the usual rapidgas intermixture (such as would produce a non-luminous combustion withno formation of carbon particles) and permits the incandescent carbonicc from 2200 to 2400 F.,-the work is moved into the furnace through theopening in wall 14. The highly heated combustion gases containingtherein strata of incandescent carbon, effect a rapid heating of theWork, the gases thereafter passing to the iiue 38 after giving upadditional heat for preheating oil and air yto be used in the process.Controlled portions ofY the flue gases are employed for directlyvaporizing the preheated-oil and for diluting the same to apredetermined heating value.

Thelowermost duct or row of burner ducts or tubes being in communicationwith the fluid fuel manifold 52, a flowing blanket `or atmosphere ofhydrocarbon vapors substantially free of oxidizing constituents coversthe work within the chamber 12, and protects the same from substantialoxidation or scaling.

An inert' or reducing atmosphere containing as much as 10 per cent COthus introduced as a owing blanket over the work to be protected fromoxidation has proved highly elTective at temperatures'around 2250? F.vand forv the required heating periods ofV around k45 minutes or less. Y1

The length of the'flames Within the furnaceA may Ybecontrolledto'uniformly distribute the heat within the chamber l'for most efficientoperation. `By increasing Vthe number of vtubes and decreasing theirdiameter While maintaining a givenratio of fluid fuel to airowingz'through the burner assembly, the'length of the-.flames can beshortened. Byv .increasing the degree of overve'ntilation the length ofthe-flames is correspondingly decreased. l The following speciicembodiment of the process is given for purposes ofV illustration-'onlyand is not intended asin any sense'limiting the scope 'of theinvention..` `Referring moreparticularly to the apparatus of Fig.hydrocarbon oil designated #2 Gulf Oil .and having' an A. P. I. gravityof C at 60 F.,a distillation range at va.niospheric pressure between.37d". and 666 F. (97% olf) and having a heating value of 140,006 B. t.u. per gallon, is purnpedfrom'the storage tank l1() to the spray nozzle.106.. During its passage to the latter, it is preheated bythe hot 'fluegases flowing to the stack through the passages 34 and 36, theconditions being so adjusted that the oil reaching the spray nozzle ispreheated to a temperature below its cracking temperature, andpreferably in the range 6002700 F. rEhe preheated oil spray from thenozzle 106 impinges upon rapidly vrevolving blades of the fan 102 whileimmersed in acontinuously flowing stream ofhot flue gases drawnfrornvthe passage 32 through conduit 12u. I

The temperatine ofthe ilue gases lio-wing past the spray nozzle 106 isadjustedfto properly temper the rich oil vapors formed in the chain berto yield a` fuel vapor mixture of uniform and preselected heating'value.vWhere oil has been preheated -to around 600 F., the 'flue gases areadjusted to have a temperatureof appioxiinately 1256 F., or somewhathigher, and are mixed with the oil spray in lchamber 100 in the ratio ofaround 5.18 pounds of the oil to 40.3 cu. ft. of flue gases. Thetemperature ofthe -hot flue gases flowing directly from thepassage'BZfmay be tempered by cooler ilue gases drawn fromthe stack 3Sthrough the valved conduit 122. i

' In many inslances it is 'desirable-to place a blower fan 142 in theconduit 120 between the line 122 and the fan chamber 100 for. thepurpose of controlling tlfiistenipering and rate offlow of the iluegases'. In any event the air and fuel vapor velocities within the burnertubes or ducts are maintained sufficiently low to avoid turbulence andto maintain streamline viscous iioiv of the hydrocarbons and air withinthe furnace adjacent the burnerv tubes. Preferably fluid fuel and airvelocities of 1G ft. per second or less are employed. ln smallinstallations the vapor velocities preferably maintaine, theneighborhood of 1 vto 4 linear ft. persec`ond.

The fluid fuel mixture ows from the chamber 100 tc the header` 52 and isthere distributed uniformlythrough certain of the. burner tubes asdescribed. Approxima'tely'1'()y to 20 perent of the total fuel vaporsemployed preferably is in,- troduced through the lovverinost row lofburner vtubes or ducts to forni a protective fluid blanket over thematerial being heattreated,

Alternating rows of ducts above thelowerrnost row'tl ereofv are incontrolled communicaion with Va source oi" air under pressre throughheader 66,#,alternate ducts in the remaining ,rows Ycpm- Vmunicatingrespectively with, thesaid source of air under pressure and with theoil-,vaporiaing chamber. 1

Air is fed to `the header 69 preferably through conduit 132 disposedwithin the regenerator char ber l36,' whereby the-air is preheated toahigh temperature approximatingthat of the. oil vapors and gases entering'the `fluid .fuel tubes from the fuel header'52. Thegvalved line134provides meansfor tempering the preheated-air with cold air to maintainat a preselected temperature the air flowing to the burnerl By suitablylregulating the velocityof the air flowing to the vheader .88 and thetemperature and volume of.-hot inert gases and oiliiowing tothe.vaporizationchainber 100, the velocities of the respectiveI'iuidstreams flowing to the furnace lthrough the burnersare maintainedapproximately the same and below the turbulent combustion range. y

y In one application of the invention Whereina 1928 u. hydrocarbonvapor-gas mixture was developed. and burnedin accordancewith thediffusion-flame or streamline 'type of Ycombustione-20 gallonsper hourYof No. 2 Gulf Oil previously described, preheated to 300 F., .wassprayed into chamba le@ in the presence of hotflue gases havingratemperature of around 1400Q F. in the proportion of 20 gallons oil yto2470 cu. ft..of the flue gases. VThe diluted fuel, vapors thus formewere flowed to and throughv the fuel ducts of the diffusioniburner at aflowv rate of approximately 2 ft. per second, well within the limits.for streamline viscous new. Simultaneouslyair was introduced nto theburner air ductsin amount to give approximately the same velocity ofowas that of the vapors. The iiue gas temperature required at atornizingchamber is considerably higher than ,that given above, where it isintroduced ccldinto the atornizingv chamber.

I v Othel1 in additionto those shownrnay be used fore ltrollingtlietemperatureand composition of Ihe hot ilue gases owing tothe atoinlzingFor instance, flue gases of Vpreselected c position highin inertsrandhaving the refrom the furnace,A tirou'gh conduit 126 andtrap tainingcompounds V.in the fiue. gases,used in vaporizing the oil assists inretarding'any carbon foijmationwit inthe fuel vapors moving through theburnernadjacent the vburner tipsdue toheat `radiated from the` furnaceinterior. Any incipient thermaldeconiposition may l'be retarded also bythe-1 troduction of superheated steam or other hot fluid into thechamber .48 of the burner of Fig. 3 Vthroughthe condu"" 58. to eliminateany considerase differences in teinperature betweenthe hot fuel vaporsowing through the burner ducts 62 and the preheated air enteringtheburnfer throng jheader 88.` A small amount of steam also Ybeintroduced in admixture with the'fuei vaporsvor with the secondary airfor' the same-purpose. f

Where an inert gas suchas nitrogen, a reducing gas such as hydrogen, or'water gasis usedinstead' of or in addition to the flue gases,lthese-gases may beV preheated to 'the required temperature by suitableVmeans, Vas by indirect heat exchange with The'presence of small amountsofoxygenconthe highly heatedy ue gases lcavingfthe furnace.v i

The invention is susceptible of modification within the scope ofthe.appended claims;Y

1. The method of operating furnaces which comprises feeding heavyhydrocarbon fuel in liquid form into an enclosed chamber whilesimultaneously atomizing the same and vaporizing at least a regulatedportion thereof by heat developed in the method, in the presence of agas low in uncombined oxygen, and atan elevated temperature near butbelow that at which substantial thermal decomposition of hydrocarbonoccurs, the amount of the said gas being proportioned with respect tothe hydrocarbon vapors to give a mixed fluid fuel having a heating valuein the range from`200 to 2000 B. t. u. per cu. ft., and thereaftersimultaneously flowing the said fluid fuel and a combustion-supportinggas into a highly-heated enclosed space in parallel contacting streamsat approximately equal velocities below the turbulent velocity range,the combustion-supporting gasfbeing present in amount at leastsufficient for the substantially complete combustion of the fluid fuel.

2. The method of operating furnaces which comprises continuously feedinghydrocarbon fuel in liquid form intoy an enclosed space while atomizingthe saine and' Vaporizing vit by heat developed in the method in thepresence of an inert gas while raising it to an elevated temperaturebelow that at which substantial thermal .decomposition of thehydrocarbon occurs', the amount of said gas being proportioned withrespect to the hydrocarbon vapors to yield a mixed fluid fuel havingauniform heating Value in the range from 200 to 2000 B. t. u. per cu.ft. and continuously and simultaneously flowing the said fluid fuel anda heated combustion-supporting gas into a highlyheated enclosed space inparallel contacting streams at approximately equal velocities below theturbulent velocity range, the said combustionsupporting gas beingpresent in amount at least sumcient for the substantially completecombustion of the fluid fuel.

3. The method set out in claim 2, in which the said contacting streamsflow at a linear vev locity not greater than 10 ft. per second.

FII

4. The method of operating furnaces, which comprises continuouslypreheating a liquid hydrocarbon, intimately mixing the preheatedhydrocarbon in` liquid form with a controlled amount of highly-heatedilue gases formed in the method while atomizing the liquid hydrocarbonthereby vaporizing the same and forming a hot flue fuel mixture ofuniform B. t. u. value in the'range from 200 to 2000 B. t. u. per cuft.,while maintaining the fuel mixture at an elevated temperature below thatat which substantial cracking of the hydrocarbon'occurs, flowing thefluid fuel 'mixture within an enclosed highly heated space of streamlineshape, in a plurality of parallel contiguous streams, alternating 1vstreams comprising respectively the-said fluid of a highly heated gasmixture low in oxidizingv constituents while atomizing the liquidhydrocarbon, thereby vaporizing the same and forming a hot fluid fuelmixture of uniform B. t. u. value in the range from 500 to 2000 B. t. u.per cu. ft. while vmaintaining the mixture at an elevated temperaturebelow '700 F. by heat developed in the method, conducting a plurality ofspaced streams of the said fluid fuel mixture along an enclosed pathfree from abrupt changes in transverse cross-section, concurrentlyconducting a plurality i spaced streams of air along the said path atsubstantially the Vsame velocity as the said fluid fuel mixture streams,the last-named streams being interspersed with the air streams toprovide contiguous non-turbulent strata of air and of the said fluidfuel mixture,progressively burning portions of the latter at theinterfaces of the same with the air during the said movement of thesestreams, and by the heat thus developed decomposing hydrocarbons in theinterior of 'each vof the said fluid fuel mixture streams progressivelyto form incandenscent carbon therein, and

to develop and transmit heat.

6. The method of operating heating furnaces, which comprisescontinuously preheating a liquid hydrocarbon, intimately mixing thepreheated hydrocarbon in liquid form with a controlled amount ofhighly-heated flue gases while atomizlng Vthe liquid hydrocarbon,therebyI continuously vaporizing the same and forming a hot fluid fuelmixture of uniform B. t. u. value in the range from 200 to 2000 B. t. u.per cu. ft., `while maintaining the mixture at a temperature below thatat which substantial cracking of the hydrocarbon occurs, flowing pastthe material to be heated in an'enclosed highly heated space free fromabrupt changes in transverse cross-section throughout its length, anon-turbulent composite fluid stream composed of al plurality ofcontiguous parallel streams respectively of preheated air and of thesaid hot fluid fuel mixture flowing at approximately the same velocity,igniting` and burning progressively portionsv of the said fluid mixtureat its interfaces with the preheated air, and maintaining around thematerial being heated and between the said air streams and the saidmaterial a' non-turbulent flowing -stream of the said fluidfuel'mixture, thereby substantially retarding oxidation of the material.

'7. The method of producingand using furnace fuel, which comprisescontinuously preheating a liquid hydrocarbon fuel, intimately mixing'the said preheated fuel in atomized form with an amount of highlyheated fluev gas produced in the process in amount suicient to vaporizeand superheat the hydrocarbons while maintaining them below theircracking temperature and while v diluting the said vapors to yield auniform fluid fuel mixture having a heating value in the range from 200to 2000 B. t. u. per cu. ft., and simultaneously flowing the said fluidfuel mixture and a preheated combustion-supporting gas into ahighly-heated space in Vparallel contacting streams at approximatelyequal velocities below the turbulent Velocity range and in proportionsfor 'substantially complete combustion, thereby i effecting vacontrolled progressive interdiffusion of the reacting constituents ofthe vsaid contacting streams to effect a combustion reaction and theformation of highly heated flue gases, and utilizing the heat of thelluegases for preheating the liquid Afuel subsequently to be used in theprocess.

8. The method of operating furnaces which `comprises continuouslypreheating a liquid hydrocarbon fuel," intimately mixing the said pre-'fic heated fuel in atomized form with an amount of highly heated fluegas sufficient to vaporize and superheat the hydrocarbons Whilemaintaining them at Va temperature below their cracking temperature andwhile continuously diluting the vapors to yield a .uniform fluid fuelmixture having a heating value in the range from 200 to 2000 B. t. u.per cu. ft., flowing the said fluid fuel mirrture and a preheatedcombustion-supporting gas into a highly-heated space free from abruptchanges in transverse cross section in parallel contacting streamsflowing at approximately equal velocities below the turbulent velocityrange and in proportions for at least substantially complete combustion,thereby effecting a progressive combustion adjacentthe interfaces of thesaid fluid streams and producing hot flue gases, and utilizing the hotflue gasesA thus produced for vaporizing and diluting the atomizedliquid hydrocarbon subseduentlyto be used in the process.

9. The method of operating furnaces, which comprises continuouslypreheating a liquid hydrocarbon fuel, intimately mixing the saidpreheated fuel in atomized form with an amount of `highly-heatedsubstantially inert gases approximately free of uncombined oxygen,sufficient to vaporize and superheat the atomized hydrocarbons Whilemaintaining them below their cracking temperatures and while dilutingthe vapors to yield a uniform highly-heated fluid fuel mii:- ture havinga po-tential `heating value within the range of 560 to 1000 B, t. u. percu. ft., thereafter simultaneously flowing the said highly-heated fluidfuel mixture and preheated air into a combustion chamber in apluralityof parallel alternating contacting streams at velocities belowthe turbulent velocity range and in proportions for at leastsubstantially complete combustion, progressively burning portions ofthesaid fluid fuel mixture at the interfaces thereof Vwith adjacent airstreams, and by the heat thus developed progressively decomposing thehydrocarbons in the interior of each of the said fluid fuel streams toformincandescent carbon while producing highly-heated flue gases,tempering the flue gases, and thereafter utilizing the tempered iiuegases for vaporizing and diluting the atomized liquid hydrocarbonssubsequently to be used in the process. .i

1Q. The me'thod of operating furnaces, which comprises continuouslypreheating a liquid hydrocarbon fuel, intimately and continuouslymisiing the said preheated fuel in atomized form with an amount ofhighly-heated flue gases in amount sufficient to vaporize and superheatat least t le major portion of the hydrocarbons while maintaining thesame below their, cracking temperature and while diluting the vapors toyield a uniform fluid fuel having a heating value in the range of from2Q() to 2660 B. t. u. per ou. Vft., separating the superheated vaporsfrom any unvapori'led hydrocarbon and removing `the latter, continuouslyflowing the former and preheated air vinto a highly-heated enclosedspace in alternate parallel contacting streams at approximately equalvelocities below the turbulent velocity range and in proportions forsubstantially complete combustion, thereby progressively burning por,-tions of the fluid mixture at the interfaces of the respective fluidstreams and, by the heat thus developed, decomposing the hydrocarbons inthe interior of each of the said fluid fuel streams to progressivelyform incandescent carbon and to develop heat and ue gases, andutilizingselected portionsof the heat of the said iiue gases for Vpendent meanscontrolling the rate air to the said ducts.

preheating the air and for preheating and volal tiliaing the liquidhydrocarbon subsequently used in the process.

11. in combination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transverse cross-sectionthroughout its length, a burner disposed at one of the said chamber andoccupying the entire end thereof, the burner having therein a pluralityof parallel ducts arranged in superpcsed rows, an oil--vaporizingchamber disposed within the furnace in communication with the4combustion chamber through certain of the said ducts,

the remaining ducts being in controlled communication with a source ofair under pressure, an oil-atomizing means within theoil-vaporizingchamber, valve-controlled means for conducting oil to theoil-atomizing'means, means for the controlled introduction of hot fluegases to the oil-vaporizing chamber, and means for removing unvaporizedoil from the oil-vaporizing chamber.

12. In combination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transverse cross sectionthroughout its length, a burner disposed at one end of the said chamberand occupying `at least Ythe major portion of the end thereof, theburner having therein a plurality of parallel ducts arranged in super'-posed rows, an oil-vaporizing chamber disposed within the furnace incommunication with the combustion chamber through certain of the saidducts, means for introducing air under pressure in controlled amountsinto the remaining ducts, means for preheating the air flowing to thelastnamed ducts, means connected with the air-introducing means fortempering the preheated-air flowing to the air ducts, oil-atomizingmeans in the oil-vaporizing chamber, means for conducting a regulatedamount of oil to the oil-atomizing means, a conduit for introducing intothe oil-vaporizing chamber a regulated amount of hot flue gases, and aseparate conduit connected with the furnace and adapted to preheatthe-oil flowing to the oil-atomizing means. Y

13. In combination, a furnace having an elongated combustion chambersubstantially free of abrupt changes in cross-section throughout itslength, a burner disposed at one end of the chamber and adapted to fillthe chamber at the said end, the burner having a plurality of ductsarranged in superposed rows, each of the ducts in the lowermost rowcommunicating with an oilvaporizing chamber disposed within the furnaceand in controlled communication with the combustion chamber through thesaid ducts, alternating rows of ducts above the said bottom row thereofbeing in controlled communication with a source of air under pressure,contiguous ducts in the remaining rows thereof communicatingrespectively with the said source of air and with the saidoil-,vaporizing chamber, oil-atomizing means in the oil-vaporizingchamber, means for the controlled introduction of hot flue gases and ofoil to the oil-vaporizing chamber, and indeof flow of 14: Incombination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transversecross-section, aburner disposed at one end of the saidfchamber, the burner having aplurality of parallel ducts arranged in superposed rows, anoil-vaporizing chamber disposed within the Yfurnace and in permanentcommunication with the vcombustion chamber through certain of the saidducts, means for the regulated introduction of air under pressure intothe remaining ducts, oil-atomizing means in the oil vaporizing chamber,valve-controlled conduit for conducting oil to the atomizing means,means for the controlled introduction of hot flue gases to theoil-vaporizing chamber, means for adjusting the temperature of the saidhot ilue gases flowing to the oil-vaporizing chamber, and means forseparately withdrawing from the oil-vaporizin'g chamber any unvaporizedoil.

15. Apparatus as in claim 14, including means associated with thefurnace for preheating air flowing to the air ducts, and means withinthe furnace for preheating oil flowing to the oilatomizing means. p

16. In combination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transverse cross-section, aburner disposed at one end of said chamber, the burner having aplurality of parallel ducts arranged in superposed rows, anoil-vaporizing chamber disposed within the furnace and in permanentcommunication with the combustion chamber through certain of the saidducts, means for the regulated introduction of air under pressure intothe remaining ducts, oil-atomizing means in the oil vaporizing chamber,a valvecontrolled conduit for conducting oil to the atomizing means,means for the controlled introduction of hot flue gases to the oilvaporizing charnber, means including a fan member for rapidly andintimately intermixing the hot ue gases and atomized oil, means foradjusting the temperatures of the said hot flue gases flowing to theoil-vaporizing chamber, and means for separately withdrawing from theoil-vaporizing chamber any unvaporized oil.

1 7. In combination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transverse cross-section, aburner disposed at one end of said chamber, the burner having aplurality of parallel ducts arranged in superposed rows, anoil-vaporizing chamber disposed within the furnace and in permanentcommunication with the combustion chamber through certain of the saidducts, means for the regulated introduction of air under pressure intothe remaining ducts, oil-atomizing means in the oil'vaporizing chamber,a valvecontrolled conduit for conducting oil to the atomizing means,means for the controlled introduc-V v tion of hot flue gases to the oilvaporizing chamber, means including a hot fan member for intimatelymixing a preselected amount of the hot flue gases with the atomized oiland for flowing the said mixture at a controlled rate into the oil vaporducts, means for adjusting the temperatures of the said hot flue gasesflowing to the oilvaporizing chamber, and means for separatelywithdrawing from the oil-vaporizing chamber any unvaporized oil.

18. In combination, a furnace having an elongated combustion chambersubstantially free from abrupt changes in transverse cross-section, aburner disposed at one end of said chamber, the burner having aplurality of parallel ducts arranged in superposed rows, anoil-vaporizing chamber disposed within the furnace and in peringchamber, the remaining ducts in the burnerr being in permanentcommunication with a source of air under pressure, oil atomizing meansin the oil vaporizing chamber, a valve-controlled conduit for conductingoil to the atomizing means, means for the controlled introduction of hotflue gases to the oil vaporizing chamber, means including a hot fanmember for intimately mixing a preselected amount of the hot flue gaseswith ne atomiZ-ed oil for flowing the said mixture at a controlled rateinto the oil vapor ducts, means for adjusting the temperature of thesaid hot ilue gases flowing to the oil-vaporizing chamber, and means forseparately withdrawing from the oil-vaporizing chamber any unvaporizedoil.

19. A furnace comprising an elongated combustion chamber having astreamline inner surface construction, a burner adjacent an end of thesaid chamber and approximately filling the same, an oil vaporizingchamber within the furnace, the said burner comprising a plurality ofsuperposed parallel ducts, means for flowing into certain of the ductsstreams of air at a controlled rate, the said oil Vaporization chamberbeing in open communication with the combustion chamber through theremaining or Huid fuel ducts, the lowermost row of ducts being fluidfuel ducts and the arrangement being such that the remaining fluid fuelducts are surrounded by air ducts, oil atomizing means within the oilvaporization chamber, means for the controlled introduction'of hot uegases into the said vaporization chamber,y means for the regulated flowof liquid fuel to the oil atomi'zing means, oil and air preheating meansoperatively associated with the furnace, and means in the oilVaporization chamber for intimately intermixing hot flue gases andatomized oil and for regulating the flow of the resultant fuel mixtureto the burner.

20. The method of operating furnaces, which ing the said fuel mixtureand a combustion supporting gas into a highly heated enclosed, space inparallel contacting streams, at velocities below the turbulent velocityrange and adapted to facilitate streamline flow of the fuel mixturewithin the furnace, the said combustion-supporting gas being present inamount at least sufcient for the substantially complete combustion ofthe fuel.

. ALBERT L. KLEES.

